How to Write a Proposal for an HSC Science Investigation

You want to investigate whether a longer pendulum takes more time to swing. Your idea sounds simple: change the string length, use a stopwatch, and record the results.

But how many swings will you time? Which variables must stay the same? And how will you know whether a difference is real or just your reaction time with the stopwatch?

These are the questions your investigation proposal needs to answer before you begin experimenting.

To write a strong HSC science investigation proposal, explain why your question is worth investigating, what you predict, how you’ll collect reliable evidence, how you’ll analyse it, and what approvals you need. You’re making a case that your investigation is scientifically useful and practical to carry out, not reporting results you haven’t collected yet.

01What is an HSC science investigation proposal?

An investigation proposal is a plan that explains what you intend to investigate and demonstrates that your method can answer your research question.

It might be part of an HSC science depth study, or your teacher might set it as a separate planning activity. If you’re unsure how proposals fit into the larger investigation, read What Is a Depth Study in HSC Science?.

The important difference is that a proposal looks forward. You’re explaining what you will do, what you expect to observe, and how you will interpret the evidence.

You aren’t expected to know the experimental result already.

What does NESA actually require?

NESA’s science syllabuses include planning scientific investigations as part of Working Scientifically. Students are expected to develop questions, design investigations, consider evidence, and communicate scientifically.

However, you shouldn’t assume there’s one mandatory proposal template used by every NSW school.

Under NESA’s school-based assessment rules, schools develop assessment programs within NESA’s requirements and provide students with assessment information. Your school’s task notification determines the particular proposal format, submission requirements, marking criteria, and deadline.

There’s also an important syllabus transition:

• The Physics 11-12 Syllabus (2025) begins with Year 11 in 2027, with its first HSC examination in 2028.
• The Chemistry 11-12 Syllabus (2025) begins with Year 11 in 2028, with its first HSC examination in 2029.

As at November 2026, students studying Physics and Chemistry are still using the 2017 syllabuses. Use the syllabus applicable to your cohort rather than assuming the newest published edition already applies.

You can verify implementation dates through NESA’s Physics syllabus and Chemistry syllabus.

The structure below is a practical writing guide, not an official NESA proposal template. Follow your teacher’s task sheet wherever it specifies something different.

02The six parts of a strong investigation proposal

Imagine your proposal is being handed to another science teacher who hasn’t heard your idea.

Could they understand what you’re testing, set up the equipment, collect useful measurements, and identify any problems before the experiment begins?

If not, something is missing.

If your task sheet provides different headings, reorganise these ideas under the required headings. The scientific reasoning is more important than matching a particular layout.

03Start with a question that determines your method

Consider two pendulums with identical bobs. One has a short string, and the other has a long string.

Which one do you predict will complete a full back-and-forth swing more slowly?

The longer pendulum should have a longer period. At the same small release angle, its bob travels a longer arc. That helps us picture the motion, although distance alone doesn’t explain the result: the gravitational acceleration along the arc also matters.

The simple-pendulum model predicts a longer period when pendulum length increases, assuming a small release angle and negligible resistance.

That’s a testable scientific prediction.

Now compare two possible research questions:

Too broad: What affects how a pendulum swings?

Better: How does pendulum length affect the time taken to complete one oscillation when the release angle and bob remain constant?

The second question tells you what to change, what to measure, and what to control.

Understand your variables

Your research question usually identifies three kinds of variables.

• Independent variable: The factor you deliberately change, such as pendulum length.
• Dependent variable: The response you measure, such as the time taken for one oscillation.
• Controlled variables: Other relevant conditions you keep consistent, such as the release angle, bob, and timing procedure.

A complete oscillation means one full back-and-forth movement. The time taken for that movement is called the period.

These variables are connected. If you change length and bob mass at the same time, then observe a change in period, which change caused it?

You can’t tell from that comparison alone.

That’s why your method needs to follow your question, rather than being written as a collection of experimental steps.

04Choose a measurement that actually answers your question

Here’s a problem that appears regularly in science proposals.

A student wants to investigate whether changing vinegar concentration affects how quickly calcium carbonate reacts.

They write:

“I’ll use different amounts of vinegar and see which one fizzes the most.”

You can picture the experiment, but what exactly does “fizzes the most” mean?

The number of visible bubbles? Their size? The total gas produced? The rate at which gas escapes?

Those measurements aren’t interchangeable.

A solution might produce lots of bubbles over a long time, while another produces gas rapidly at the beginning and then stops.

The first idea is useful, but the measurement needs to be more precise.

05Plan your analysis before collecting data

A common proposal mistake is to write a detailed practical method, then finish with:

“The results will be put into a graph and analysed.”

That doesn’t tell your teacher much.

Instead, decide what each measurement will mean before the experiment begins.

For the pendulum investigation, you need a table containing length, repeated timing measurements, calculated periods, and mean periods.

For the chemistry investigation, you need the vinegar dilution, elapsed time, collected gas volume, and trial number.

Your planned analysis should answer three questions:

1. What relationship am I looking for? For example, whether increasing pendulum length increases the period.
2. How will I recognise it? For example, by comparing mean periods and examining a period-versus-length graph.
3. What else could explain the measurements? For example, inconsistent release angles, timing errors, or differences in the apparatus.

Think of your graph as a way to test the prediction, not as something you add to make the report look scientific.

If your teacher allows a secondary-source investigation instead of a practical experiment, the same principle applies.

Name the data sources you intend to use, explain why they’re credible and comparable, identify what quantities you’ll extract, and specify the comparison or analysis you’ll perform. Don’t promise measurements that the sources don’t provide.

For a broader explanation of how questions, methods, and evidence fit together, see What Is Working Scientifically in HSC Physics and Chemistry?.

06Include feasibility, risks, and approvals before submission

A proposal can contain an excellent research question and still be unsuitable for a school investigation.

Perhaps the equipment isn’t available. Perhaps the measurement is too imprecise. Or perhaps the investigation requires permission that hasn’t been obtained.

That’s why feasibility and safety need their own place in your proposal.

The NSW Department of Education’s science safety and compliance guidance discusses risk assessment and chemical safety in schools. Your teacher and school determine the procedures and permissions applicable to your investigation.

Consider the difference between these two statements:

“The experiment is safe because vinegar is a household substance.”

“The method uses diluted vinegar in a supervised laboratory. Potential risks include spills, eye contact, glassware breakage, and problems with gas-collection equipment. The quantities, protective measures, disposal procedure, and apparatus will be checked with the teacher before the practical.”

The second statement recognises that familiar materials can still create hazards in an experimental setup.

For investigations involving people, animals, environmental sampling, external facilities, or potentially sensitive information, ethical issues and further permissions may arise. Don’t assume that school approval automatically provides permission to enter a site, use someone else’s data, or conduct an activity involving participants.

A final proposal checklist

Before submitting, work through these checks:

• [ ] My rationale connects the investigation to relevant scientific knowledge and includes appropriate references.
• [ ] My research question identifies a clear, measurable relationship or comparison.
• [ ] My prediction is supported by scientific reasoning rather than an assumed result.
• [ ] My method states what will be measured, how variables will be controlled, how many trials are planned, and what equipment and time are needed.
• [ ] My proposed calculations, tables, or graphs can actually answer the question.
• [ ] I have identified limitations, risks, ethical issues, and any permissions required. I have not treated proposed approval as approval already granted.
• [ ] I have followed my school’s task notification, including its submission instructions, academic integrity requirements, and deadline.

If one of these points fails, revise the proposal before investing time in the full investigation.

A shorter question with a defensible method is usually more useful than an impressive-sounding question your equipment cannot answer.

07Questions and solutions

These questions move from basic proposal writing to more difficult problems involving experimental design, misleading measurements, competing explanations, and the limits of scientific conclusions.

Question 1

A student wants to investigate how water temperature affects the time taken for sugar to dissolve.

They plan to use 5.0 g of sugar in 100 mL of water at temperatures of 20°C, 30°C, and 40°C. The stirring method will remain constant.

Write:

a) A suitable research question.

b) The independent and dependent variables.

c) Two controlled variables.

d) One appropriate method of presenting the results.

Solution 1

A suitable question is: “How does water temperature affect the time taken for 5.0 g of sugar to dissolve in 100 mL of water under a consistent stirring procedure?”

a) This is testable because the student can deliberately change temperature and measure a defined response.

b) The independent variable is water temperature, measured in degrees Celsius. The dependent variable is the time until no visible sugar crystals remain, measured in seconds.

c) Two controlled variables are the sugar mass, kept at 5.0 g, and the water volume, kept at 100 mL. Sugar particle size and stirring procedure should also remain consistent.

d) The student could calculate the mean dissolving time from repeated trials at each temperature and plot temperature on the horizontal axis against mean dissolving time on the vertical axis.

The tempting mistake is to claim that the experiment measures the rate of a chemical reaction. Sugar dissolving in water is a physical dissolution process, and the proposed endpoint is the disappearance of visible crystals.

The proposal should describe what is actually being measured.

Question 2

A Physics student proposes investigating whether illumination from a desk lamp decreases according to an inverse-square relationship as distance increases.

During a hypothetical preliminary measurement, a light sensor gives the following readings:

The student argues:

“Doubling the distance only halved the illuminance, so the inverse-square relationship must be wrong.”

a) Evaluate this claim after accounting for background illumination.

b) Explain two conditions that would need attention before the student could make a defensible investigation proposal.

c) Suggest a graph that would test the proposed relationship more thoroughly.

Solution 2

The student’s conclusion is not supported by these readings. Once background illumination is removed, the lamp’s contribution is consistent with an inverse-square relationship at the two tested distances.

Part a: Correct for background illumination.

Assuming the background remains stable and the sensor responds appropriately, the lamp’s contribution is:

\[ E_{\mathrm{lamp}} = E_{\mathrm{on}}-E_{\mathrm{off}} \]

Here, \(E\) represents illuminance, measured in lux.

At 0.50 m:

\[ E_{\mathrm{lamp}}=180-60 =120\ \mathrm{lux} \]

At 1.00 m:

\[ E_{\mathrm{lamp}}=90-60 =30\ \mathrm{lux} \]

Doubling the distance reduced the lamp-only illuminance to one-quarter of its original value.

For an ideal point source, illuminance perpendicular to the incoming light follows:

\[ E\propto\frac{1}{r^2} \]

Here, \(r\) is the distance from the source in metres.

Doubling \(r\) predicts one-quarter of the original illuminance, which matches the corrected values.

Part b: Improve the method.

First, the proposal must control sensor orientation and background lighting. The lamp and sensor should remain aligned, and background readings should be taken appropriately at each measurement position.

Second, the lamp isn’t a perfect point source, especially at short distances. Its size and light distribution can affect the relationship. The student should choose a suitable distance range and recognise this limitation.

Repeated readings would also help quantify random variation.

Part c: Plan a stronger analysis.

Measure corrected illuminance at several distances and graph it against \(1/r^2\), where \(r\) is measured in metres.

An approximately straight-line relationship would support the proposed model within the tested conditions.

The trap is treating total sensor readings as if they came entirely from the lamp. Correcting that measurement changes the interpretation, but agreement at only two distances still isn’t enough to establish a general physical law.

Question 3

A student wants to investigate whether changing the mass of a pendulum bob changes its period.

They use two spherical bobs:

• Bob A has a radius of 1.0 cm and a mass of 20 g.
• Bob B has a radius of 3.0 cm and a mass of 80 g.

For both pendulums, the student measures 0.80 m from the pivot to the top of the bob. They keep the initial release angle small and constant.

After obtaining slightly different periods, they conclude that bob mass affects the period.

a) Identify a variable the student has unintentionally changed.

b) Calculate the effective pendulum lengths, measured from pivot to centre of bob.

c) Design a more valid comparison and state what the simple-pendulum model predicts.

Solution 3

The result cannot be attributed to bob mass alone because the student has also changed the effective pendulum length.

Part a: Identify the hidden variable.

A simple pendulum’s length is measured from the pivot to the centre of mass of the bob, not merely to the top of the bob.

The two bobs have different radii, so equal pivot-to-top distances do not produce equal pendulum lengths.

Part b: Calculate the lengths.

For Bob A:

\[ L_A=0.80+0.01 =0.81\ \mathrm{m} \]

For Bob B:

\[ L_B=0.80+0.03 =0.83\ \mathrm{m} \]

Here, \(L_A\) and \(L_B\) are the effective pendulum lengths for the two bobs.

The larger, heavier bob also has a longer effective pendulum length.

Part c: Redesign the comparison.

A better method would use spherical bobs of approximately the same external size and shape but different masses, such as bobs made from materials of different densities.

The student should set the same pivot-to-centre length, initial angle, and release method, then record repeated periods.

For a simple pendulum at small angles:

\[ T\approx2\pi\sqrt{\frac{L}{g}} \]

Here, \(T\) is the period in seconds, \(L\) is the pivot-to-centre length in metres, \(g\) is gravitational acceleration in metres per second squared, and \(\pi\) is a mathematical constant.

The model predicts that mass does not affect the period when the effective length and gravitational conditions remain constant.

Real bobs have finite size and experience air resistance, so this prediction is an approximation, not a guarantee of identical measured times.

The central problem is experimental confounding: the student changed two relevant characteristics together. More stopwatch trials would improve the precision of the measurements, but they would not separate the effect of mass from the effect of length.

Question 4

A student proposes investigating whether a stormwater outlet increases the salt concentration in a creek.

Their plan is to visit the creek after rain, measure electrical conductivity once at a point 5 m upstream of the outlet and once at a point 5 m downstream, and compare the readings.

A partner suggests taking ten conductivity readings at each location instead, arguing that this would prove whether the outlet causes the difference.

a) Explain why neither plan can establish the claimed cause.

b) Rewrite the question so that it matches what the available measurements can support.

c) Propose a more defensible sampling and analysis plan.

d) Explain how permissions and safety might affect whether the investigation can proceed.

Solution 4

Neither plan can demonstrate that the outlet causes an increase in salt concentration. Repeated readings may improve measurement precision, but they don’t remove the uncertainty about what caused any difference between the sites.

Part a: Identify the problems.

Electrical conductivity indicates how readily water conducts electricity, which depends on dissolved ions and temperature. It does not uniquely measure the concentration of one particular salt.

A higher downstream conductivity reading could arise from the outlet, but also from other inflows, natural differences in water chemistry, mixing, or changes in flow.

Taking ten readings at the same locations reduces some random measurement uncertainty. It does not automatically create ten independent samples or eliminate those alternative explanations.

There is also a timing problem: sampling after rain could be unsafe, and the creek’s conditions may change rapidly.

Part b: Rewrite the question.

A more defensible question would be:

“How does water conductivity differ between selected upstream and downstream locations near a stormwater outlet under specified sampling conditions?”

This asks for a measurable spatial comparison without assuming the cause or pretending that conductivity measures a single salt.

Part c: Improve sampling and analysis.

A revised plan could use several suitable upstream and downstream locations, with repeated independent samples collected across multiple approved sampling occasions.

The student should standardise sampling depth, recording procedure, and conductivity measurement conditions, including temperature correction where appropriate.

The planned analysis could compare conductivity between locations and sampling occasions, using graphs and summary values while noting rainfall and flow conditions.

Even with this stronger design, establishing that the outlet caused a difference would require additional evidence about the water entering the creek and other possible sources.

Part d: Address approvals.

The teacher must approve the fieldwork risk assessment. Safe access, weather, water conditions, supervision, and permission from any relevant landowner or site authority must be considered.

Students should not enter unsafe flowing water or assume they can access a site simply because it is near their school.

If access is unsuitable or permission cannot be obtained, the student could propose analysing suitable existing water-quality data, subject to the school’s assessment requirements.

The tempting assumption is that more readings automatically mean stronger causal evidence. Repetition can reduce random uncertainty, but it cannot repair a fundamentally limited comparison.

Question 5

A Chemistry student proposes investigating whether stirring water increases the chemical reaction rate of an effervescent tablet.

The proposed apparatus consists of a flask containing 200 mL of water connected to a gas syringe. The same type and mass of tablet will be used in each trial.

One condition involves stirring the liquid, while the other leaves it still. The student plans to maintain the same temperature, use identical equipment, alternate the trial order, and repeat both conditions.

In hypothetical preliminary data, the stirred trials consistently reach 60 mL of collected carbon dioxide sooner, but both conditions eventually reach the same collected volume of 80 mL.

The student argues:

“Because the final gas volumes are equal, both reactions produced the same amount of gas. The stirred reaction reached that amount faster, so stirring must have increased the chemical reaction rate.”

Another student offers a different explanation:

“Stirring could simply make dissolved carbon dioxide escape into the syringe faster, even if the gas is being chemically produced at the same rate.”

a) Can the proposed measurements distinguish these explanations? Explain carefully.

b) What scientific claim is directly supported by the proposed measurements?

c) Suggest one useful follow-up control and explain exactly what it could, and could not, establish.

d) If the school only has gas syringes and no independently validated method of tracking reaction progress, how should the research question be revised?

Solution 5

The gas-syringe measurements cannot distinguish the two explanations. They show how quickly carbon dioxide enters the collection apparatus, but they do not independently reveal how quickly the chemical reaction itself proceeds.

This distinction is crucial, even though the experimental controls appear strong.

Part a: Explain the competing mechanisms.

There are at least two possible processes:

1. The tablet undergoes chemical reactions that produce carbon dioxide.
2. Carbon dioxide moves from the liquid into the gas phase and eventually enters the syringe.

Some carbon dioxide can remain dissolved in water rather than immediately entering the syringe.

Stirring might increase the reaction rate by improving contact and mixing between reactants. But it could also increase the transfer of already-produced, dissolved carbon dioxide into the gas phase.

Both mechanisms could produce a steeper gas-collection curve.

Even a perfectly leak-free apparatus wouldn’t solve this problem because the gas syringe does not measure the dissolved carbon dioxide directly.

The equal final syringe volumes do not resolve the ambiguity either. Both proposed mechanisms can be consistent with the same eventual collected volume.

This is the difficult point: controlling external variables and obtaining repeatable results does not guarantee that a measurement uniquely identifies the process you want to study.

Part b: State the supported conclusion.

The defensible conclusion would be:

“Under the investigated conditions, stirring increased the rate at which carbon dioxide was collected in the gas syringe.”

That conclusion describes the observable measurement.

It does not establish how much of the effect came from a change in reaction rate and how much came from faster release of dissolved gas.

Part c: Consider a useful control.

One possible follow-up would use equal samples of water containing dissolved carbon dioxide, with no reacting tablet present.

The student could compare gas release under stirred and unstirred conditions using an appropriately designed, teacher-approved collection system.

If stirring increased gas release in that control, it would demonstrate that stirring can influence the measurement even without a chemical reaction producing new carbon dioxide.

However, this control still wouldn’t tell the student precisely how much of the difference in the original reacting system came from increased reaction rate.

To establish that, the investigation would need an independently validated way to monitor chemical reaction progress, rather than relying only on gas entering the syringe.

Part d: Revise the research question.

If a suitable independent method isn’t available, the scientifically defensible revision is:

“How does stirring affect the rate of carbon dioxide gas collection from an effervescent tablet in water under controlled conditions?”

This is a narrower question, but it can be answered using the proposed equipment.

Collecting more repeats would help establish whether the observed gas-collection difference is consistent. It would not separate chemical production from gas transfer.

The strongest proposal is therefore not necessarily the one with the most ambitious original claim. It’s the one that recognises exactly what the equipment measures and designs the question around evidence that can genuinely support the conclusion.

Once your teacher approves the proposal, your next job is to carry out the agreed method, record the actual observations, and evaluate whether the resulting evidence is strong enough to answer the question you set out to investigate.